Preheat the oven to (400°F or 190°C) degrees.
Use two pie pans or two shallow containers. In one pan place the warm clarified butter. In the other, add the dry blackening seasoning mix.
Take one fillet at a time and dip it into the clarified butter. (In these photos, I'm only dipping one side into the seasoning mix because of the thickness of the halibut fillets. You can, if you wish, dip both sides into the butter and seasoning mix for a more robust seasoning flavor.)
Turn on the overhead vent for your stove. If you don't have one, you may want to do this outside over a camping stove because it can create a lot of smoke.
Get a dry heavy cast iron pan super hot until smoking. DO NOT ADD OIL to the pan as it will catch fire!
Without losing any of the seasonings, add the fish to the hot pan seasoning side down. The combination of the cold fish and the clarified butter will cause the fish to float almost over the high heat of the pan without sticking.
Cook the fish until the seasoning is slightly charred black in spots. At this point, I gently flip the fish and place it in a cooking dish with a little butter, white wine, and lemon juice.
Place the fish into the oven at 400 degrees to finish cooking the halibut all the way through...about 8-10 minutes in this case. Check with a meat thermometer until the fish has reached an internal temperature of 145 degrees.